Starting from version 0.4.0 XMvn is configured using XML configuration files instead of environmental variables. The configuration model was built using Modello and it's fully documented. The XML model supports new configuration options, it's more flexible and has new features, such as inheritance of different configuration files.
Prior to version 0.4.0 XMvn used to be bootstrapped using a custom launcher code. In version 0.4.0 XMvn Launcher module was dropped and bootstrapping process was migrated to standard Classworlds launcher. Now the bootstrap process can be controlled with standard m2.conf file.
Now XMvn site is created from XMvn POM using Maven Site Plugin. It contains much more detailed information about the project, including release notes, Javadocs, source cross-reference and much more.